Carbon materials such as activated carbon, carbon nanotubes, carbon nanofibers, fullerenes, and graphene are used as support for heterogeneous catalysis because of their large specific surface area, good porosity, high electron conductivity, and relative chemical inertness. The composition of these materials with metal nanoparticles has attracted huge attention in catalytic hydrogenation because of their excellent electrical, thermal, optical, and mechanical properties as well as high surface-to-volume ratios. Specifically, metal-carbon nanotube-based nanocomposite has demonstrated extraordinary catalytic activity in hydrogenation reaction by virtue of the integration and synergetic effects between both materials. Highly valuable products applicable for pharmaceutical, biomedical, and agricultural industries are produced from the catalytic hydrogenation reactions. Consequently, the demand for metal nanocomposites has been increasing rapidly, and particular attention is required for advanced synthesis techniques and to understand the real factors responsible for high catalytic activity. This chapter includes the significant advances that have emerged in this field and aims to explore the catalytic-activity-dependent factors and their prospective application in the hydrogenation reaction. © 2020 American Chemical Society.